Carburetor



l0 Sheets-Sheet 2 CARBURETOR Filed July 10, 1918 k March 15,1927. '1,620,827

F. C. MCK ET AL CARBURETOR Filed July 10. 1918 l0 Sheets-Sheet 3 j .f on @a 1,620,827 F c MocK ET AL CARBURETOR med July 1o 1918 -10 sheets-sheet 4 Chale QT Guaafofu L. Cim/mum" lm mugs riimh- 15,1927..

March. 15, 1927. F.' C. MDCK ET AL CARBURETOR Filed' July 10, 1918 10 Sheets-Sheet 5 March 15,1927. A1,620,827

F. C. MOCK ET AL CARBURETOR Filed July 1o. 191s 1o sneets-sheet e A auf, a

March 15, 1927. F C, MOCK ET AL CARBURETOR Fild July l0, 1918 l0 Sheets-Sheet '7 @mmm Wl/71)@ C. 7710,07@

1,620 827 March 15,1927. F* c. MDCK ET M CARBURETOR Filed July 1o, 1918 10 Sheets-Sheet 8 Q9 11b Y 260 5 95v 19), 95a, w l f* .//w Lru March 15, 14927D 1,620,827

F. C. MOCK ET AL vCARBURB'IOR Filed July 10, 1918 10 Sheets-Sheet 9 L] /99 9o L 12a 9b i .420 maw/.vf .00* mim /99 E' @b |=`i Q0* max. I .oofmi/m i zal 7?/ A @mm/bons F75-mm C. mam Uuml/.5 c7. lw'zafimm w .Chandier [By l k March 15, 1927.

F.C. MOCK ET AL.

CARBURETOR Filed July 10, 1918. 10 Sheets-Sheet 10 c5311) f mm c. mm1@ Chcwlw @I @wia/son dtorneub Patented Mar. 15, 1927.

UNITED STATES FRANK C. MOCK, CHARLES J. GUSTAFSON,

ILLINOIS, ASSIGNORS TO STROMBERG PATENT OFFICE.

ILLINOIS, A CORFORATION OF ILLINOIS.

CARBURETOR.

Application filed July 10,

Qur invention relates to carburetors.

The primary object of the invention is t 0 provide an improved carburetor, such as 1s den'ianded for aeroplane motors.

The particular enibodiment which we shall neseribe in detail laer provides two outlets as are required for engines having two sets of cylinders and two n'ianifolds.

The severe and unusual conditions of usage demanded by aeroplane work have required changes in structure and function of the carburetor and have required operation of the carburetor under conditions not to be found in any oher class of service'.

The most unusual condition is the variation of air pressure. Carburetors in general have te do with mixing of the liquid fuel and air. As the carburetor enters a region where the air is under less pressure and is less dense, the proportions of air and liquid fuel tend to vary to the detriment of the working of the engine. For any given engine speed the veight of air fiowing past a given point decreases proportionately with the density,

V but the liquid flow influenced by the air decreases as square root of the density of air. Therefore, in localities of rarefied air the fuel to air proportion is increased forming too rich a mixture.

`We have provided a manual control of the pressure on surface of the liquid fuel in the float chamber for controlling the effective head of liquid and thus it is possible to make adjustment for the change in atmospheric condition so as to maintain aproper mixture. It is apparent that mechanical adjustment of the size of the liquid fuel orifices could be made, but we have found such adiustment to be impractical. l Furthermore where more than one carbur is provided it is practically impossible to securelilie metering of both instruments. The means which we have provided permits of the adjustment of any number of carbu* refers from a common point, to the setting desired and to any degree of accuracy required. vWe have further provided automatic means for exercising the control in accordance win pressure and with temperature of the atmosphere.

IVe have further provided a novel rela- 1918. Serial No. 244,231.

tion of air bled jet and suction control of the pressure on the fuel in the float chamber which permits of a wider variation of the effective head of fuel in the float chamber than has heretofore been possible. Ve employ a double venturi for breaking up and properly mixing the liquid fuel with the air. The fuel nozzle enters the inner venturi and is therein subjected to a maximum suction. inunicates with theouter venturi and is subjected to a definite proportion of the maximum suction. The jet is air bled and this reduces the effective suction upon the gasoline from the float chamber. Consequently the pressure variation possible upon the gasoline in the fioat chamber becomes a much greater .factor in controlling flow.

Another unusual condition met in aeroplane practice is the tilting of the carburetor sidewise when the aeroplane is caused to sideslip on an angle. Another condition is the fore and aft tilting of' the carburetor caused by climbing or diving of the aeroplane. Another condition to be met is the requirement for large free passages of air, necessitated by maximum demand for power, and particularly desirable under reduced air pressures at greater altitudes.` rThe nature of the mounting of the carburetor and the lack of any stable foundation or heavy frame entails vibration to a greater degree than would be tolerated in automobile or other practice.

These conditions, as well as others, are overcome by our present invention. Particularly for meeting the conditions of tilting both sidewise and fore and aft, we provide a novel arrangement of the air inlet, the .fuel jets, the float chamber, the float and float valve. le provide novel means and arrangement of parts for governing the feed of the fuel ets by controlling the degree of sub-atmosphere prevailing in the float chamber, independently ofthe distribution of the fuel between jets. The iioat chamber, floaty and valve of our invention are all particularly adapted for aeroplane and similar service, although we do not intend the invention to be limited to such use.

We have observed that in earburetors of The top of the float chamber coin-- the prior art, in which an idling jet and a main or working et are employed, there isI a tendency to iorm an unsatisfactory mixture when the throttle is partly opened.l rfhis occurs particularly where the carburetor is made with a fairly large air passage through the 'carbureti'ng chamber. ln such devices, itappears that a partial opening of the throttle cuts down the output of the idling jet without gaining a sutiicient increase in the functioning of the main jet to provide a proper mixture. 1We have provided a novel arrangement of the idling jet in connection with thethrottle and thc main et, to insurefproper coordination' of the jets to i'orm the proper mixture for all positions ot' the throttle valve.

Numerous other improvements will be apparent from the following specilication and claim."

In the accompanying drawings, which forma vpartofthe present specilicat-ion, we have illustrated on'eembodiment in which our invention may appear.

Figure :1 is atop-plan view of a device embodying lour invention;

Fig-ure`2 vis a longitudinal vertical sectio'nv of `the same taken on the line 2-2 of Figure 1;

Figure 3 is a Atransverse vertical section taken on the line 3-3 of Figure 1;

Figure 4is a transverse section through one of the units on the line 4-4 of Fig'- ure 1;

Figurel 5 is an elevational view of the mainf'venturiwith the suspension for the secondary venturi;

Figure 6 is a perspective view of the springV ring for holding the supporting spider for the secondary venturi upon the main venturi Figure 7 is a section of a modilied form of mai-n' jet;

Figure 8 is a similar sectional view of another modification;

Figure 9is a vertical section through the idling jet taken on the line 9-9 of Figure 1;

FigurelO is an enlarged detailed view of the'same;

Figure 11 is an elevation oi the -idling jet nozzle;

Figure 12 is a fragmentary detail of construction of the holding means for the idling control valve;

Figure 13 is a sectiony of the float chamber control valve on the line 13-13 of Figure 1;

Figure14 is a plan view of the valve disc shown in .section in Figure 13;

Figure 15 is a sectional view taken on the line15-15 of Figure 3;

Fig-ure 16Ais a plan' view of the lever for the float-valve;

Figure 17 is a left side-elevation of a modification;- f y v Figure 18 is a tcp plan view ot' the saine;

Figure 19 is a vertical cross .sectional view;

Figure 2O is a fragmentary elevation ot the adjusting means for the idling jet;

Figure 21 is a vertical sectional view on the line 21-21 of Figure 18;

Figure 22 is a fragmentary sectional view taken on the line 22-22 of Figure 21;

Figure 23 is a diagram illustrating the application of the operators control valve to the ioat chamber of two carburetors operating in unison;

Figure 24 is a diagram illustrating the application ci? the operators control valve, and a central control chamber, to a number ot' carburetors operating in unison;

Figure 25 is a diagram indicating in connection with the diagram of Figure 26 the increased controlling eilect which is obtained by an air bled jet in connection with the operators control valve; and

Figure 27 illustrates in section automatic means tor-controlling the pressure governing valve.

The particular embodiments illustrated areada ated to be employed with the usual V-shaped aeroplane engine, having 'twin sets of cylinders with the carburetor disposed within the V. We do not, however, intend to limit the invention to such use.-

The body oi the carburetor, shown in the drawings, is divided into two main sections, namely7 the lower or air intake section 1, and the upper or throttle housing section 2, both ot these sections having a portion of the float chamber 3 disposed therein. rlhe lower section 1 has an enlarged mouthv or air opening 4, facing forward. The inlet 4 is entirely open to the atmosphere and is ot a size suitable to take in air for both units 5 and 6, without choking or interference.

The intake 4 may be connected to a suitablel hot air connection; provision being made tor-this at the screw sockets 7 and 8, shown in Figure 4.

The throttle housing section 2 provides the outlets 10 and 12 which are governed by suitable throttle valves 11 and 13 of the usual or any preferred construction. These throttle valves are in practice connected together so that they may be operated simultaneously.

"he body of the carburetor, courrising both sections 1 and 2, is preferably niade ot' aluminum. The shatts 14v and 15 o'i' the throttle valves 11 and 13 are mounted in brass or 4bronze bushings 1S to reduce wear.

rl.`he 'float chamber 3 is termed oi a lower section 17 integral with the lower casing section 1,Y and anA upper portion 13 integral with the upper section 2. The float chamberitselfis ormedin .theshape cia short drum or cylinder with thecorners rounded, lying on its side.4 The float 20iso3ta siniilar shape, though smaller in size so as to lill) have room for play within the float chainber. The float is shown in Fig. 2:3 in the position which it occupies when the valve controlled thereby is closed. During operation of the engine fuel is use-d quite rapidly and the float drops down a. slight distance sufficient to permit the requisite flow of liquid fuel to pass the valve 29. hen in such lower position i. e. when the engine is in operation and drawing fuel, the part of the float chamber' in which the liquid level will stand for the various operating positions of the plan-e, is substantially symmetrical about the float. The float 2() is made up of two sheet metal sections 2l and 22, joined by a tapered overlapping joint as shown in Figure 2. The portion has a beveled edge and t-he portion 2l has a tapered shoulder which engages the beveleil edge and a cylindrical part fitting within the open edge of the section 22. This joint is brazed to secure av tight union.

The float 'is joined to a float lever or forli 24 by means'o'f a foot or plate which is formed integral with the lever 24. The lever 24, as shown in Figure 16, is stamped out of sheet metal having the foot or plate 25 and the two arms 26 which are connected together by the shouldered rivet 28 which forms the connection with the needle valve 29. The outer ends of the arm 2o are mounted upon a shouldered bearing sleeve or bushing 30, the ends of which tit snugly between the boss 3l formed on one side and th-e removable plug 32 on the other side. A pin or shaft 33 forms the fulcriun for the lever 24,-this pin or shaft beng preferably secured to the removable plug 32 and having its inner' end seating in a recess in the side walls.

The needle valve 29 comprises a stem 35 having a slot 36 in the. lower end thereof. The spring plunger 37, slidable in the bore of the'body 35, is adapted to be pressed aOainst the pin 28 to hold the stem of the needle valve in pivotal connection with the lever 24. The portion 17 of the float chainber communicates with the compartment 42, which is formed in the lower part of an extension or casing 40, formed on the lower body portion 1. A gasoline receiving chamber 41 is formed in the upper part of the casing 40,-the chambers 41 and 42 being separated by tbe wall 43. A valve seat member 44 in the shape of a plug and having a valve port 45 provides communication between the receiving chamber 4l and the floatchamber proper.

rlhe upper end of the valve stein 35 bears a hard metal tip 46 which co-operatcs with the valve seat 44. rlhe top of the receiving chamber 41 is closed by cover member 47, having a suitable connecting nipple 48 which is connected to the gasoline pipe leading from the main tank.

The construction of the float and float valve novel and is designed to secure freedom from difficulties heretofore encountered in carburetors for aeroplane engines and the like. lt will be noted that the valve 35 is placed as near the float 20 as is feasible. The spring` connection between the movable valve plug and the float is such that the valve will not chatter and pound the valve seat and wear the same out, due to vibrations of the device, as has heretofore been experienced. Movement of the valve with the float in. a downward direction is secured by a positive connection, this motion does not, in any way, affect the valve or seat.

Access to the float valve is provided by the removable plug 50 in thel bottom of the chamber 42, directly below the valve so that by dropping the float 20 to its lowermost position and moving the valve 35 sidewise from the pin 28, the valve may be removed.

The float chamber' and float are of such construction and proportions as to operate under a great variation in position such as will be met in aeroplane worl. As the float is cylindrical and as the valve is placed very close to the float itself, inclination of the carburetor' in a fore and aft manner does not interfere with the operation of the device, except in the extreme positions. rl`he float 20 is of relatively large size so that even in the extreme position the necessary force to.

operate the valve is secured by the buoyancy of the float. rlhe float 2O lies above the lever 24 so that even if the aeroplane should dive vertically, the float would have effective lever arm with respect to the pivot 28 and would govern the flow of gasoline thru the valve.

There is a unique coordination in the rela-` tion of the means for maintaining the fuel level and 'the nozzles rl`he float 2() is shown as drum-shaped. Being drum shaped, it is symmetrical about its longitudinal axis, and that axis is normally horizontal. The float is made of such width, diameter and weight that the plane of flotation i. e., the plane of the surface of the liquid fuel in which it floats, passes substantially through the longitudinal axis of the float when the carburetor is in normal upright position. Then in order to keep said plane of flotation and said float axis substantially in coincidence when the plane in which the cai/'bureter is carried, noses either up or down i. e., is tilted fore and aft, the fuel level must swing about a horizontal axis which is subH stantially coincident with the line between the outlets of the two nozzles and which if; also substantially coincident with the horizontal axis of the float in normal position. rlhis is accomplished by making that part of the chamber which during normal operation contains the liquid fuel level substantially symmetrical about the same axis as -rli lll)

that about which. thev tloat is symmetrical. tvince the vfloat is. drum-shaped the part ot the lloat chamber in which the liquid level lies for the various operating positions ot the carburetor, is likewise substantially drum-shaped. Thus the desired result ot having the liquid level stand substantially on the horizontal line joining the nozzle openings is accomplished for normal ope ation ot the carburetor whether the plane is level or nosed up or nosed down.

The main nozzle units and 56 are mounted in the lover part of the carburetor axially in line with the outlets l0 and l2.

lille shall describe the structure ot' the unit 56 only, as these units are similar in construction. r'he nozzle unit 56 is provided with a well casing 57 formed integral with the body section l. rlhis well casing e5:- tends down below the bottom of the body l, being closed by a. plug 58. An inclined passageway' 59 (see Figure l) having a metering restriction 60, communicates with a horizontal passageway 61, which leads into the bottom ot the float chamber (see Figures $3 and rlhe diagonal passageway 59, between the bottom of the well casing and the horizontal passageway 6l, is threaded internally and is arranged to receive a screwplug 60, which has an orifice therethrough tor limiting the discharge ot fuel from the nozzle unit. This restriction is better trom a n'iechanical standpoint than an adjustable valve, because it is very difticult to adjust a plurality ot' valves to the same discharge. rl`he plug 60 may be removed and another substituted, tor changing the capacity of the orilice. rlhe upper end of the diagonal passageway is closed by a removable plug 69..

The interior `ot the well casing 57 is divided into two compartments, namely, the normal well 63 and the accelerating well 64. These compartments are separated by a sleeve member 65, which has a threaded head member 66 screwing into the interior ot the well casing. The main nozzle 67 extends upward through the sleeve and through the top of the well casing, having a separable tip 68 secured upon its upper end by screw threads.

The nozzle 67 comprises a tube or sleeve having a shoulder 69 at its lower end, adapted to engage in a recess in the head 66 tor holding the walls of the nozzle 67 away 'trom the walls 'ot the sleeve 65. Near its upper end the nozzle 67 is provided with a. slightly enlarged portion 70, which closely within the top ot the sleeve so as to hold the sleeve 65 and the nozzle 67 concentric with cach other but with a small annular space between them to permit air to move trom the accelerating well into said space and through series or small oritices 7l which are formed in the side walls ot "he nozzle 67 just below the enlargement 7C'.

The sleeve 65, which vdelines the accele ating well 64, is pierced' by al number of holes 72 through the side walls, these holes preterably being arrangedfin vertical rows. series ol small openings 7 El Y are formed through the side walls ot the nozzle 67 near its lower end, so that, communication is allorded between the normal well and tho accelerating welly 6st.y The tip 68,*is provided with a series of rholes 75 in the side walls immediately,adjacent to the top o t' the tip.

A small bleeding chamber 76 is formed about the upper en d of the sleeve, this bleeding chamber comn'iunicating with the interior of the'nozzle 67 by means ot thev bleedinO o )eninO's 77 which are rot' small size D. m and which are arranged around the sides or the nozzle within the bleeding` chamber.l

The bleeding" chamber 76 communicates with ahorizontal passageway 78 which in turn communicates with the atmosphere through vertical passageway 79 in the air inlet plug lt will be seen that air is ad missible to the nozzle 67 'by way ofthe bleeding olieningsr77, passageway 7 n8, and vertical passageway :9; a nozzle, 'ot this nature, wherein airis admitted to it, is known as an air-bledi nozzle. Y

The air inlet tube' 8O is threaded into an opening in thebody ot the carburetor. The lower end y,of the plug is' adapted to seat at Sl in the metal lof the body and this lower end has a calibratedorilice 82 which communicates with. a horizontal bleeding passageway 83, tor bleeding theaccelerating well. The intermediate'v portion of the plug 80l is reduced as shown in Figure 4l, to provide an annular space between the side walls ot the hole in which the plug is secured andthe sides ot the plug. This annularspace communicates at its lower end withthe horizontal passageway 7S and.communicates with the bore'79 vo't' the plug by way ot a calibrated orifice 84;.,

The bore 79r communicates with the interior of the intake l by way of' passage 9 2 and this partales of the same pressure conditions that prevail about the main air intake. The plug closes oil the hole in which the inlet tube 80 is seated.v

Air entering y way ot-the bore 79 ot the plug 80 is free to enter the accelerating well tor bleeding the same or tobe drawn into thebleeding chamber 76 tor breaking up the stream otiuel through the nozzle 67 and ttor compensatingthe mixture. i

The nozzle unit 56 is provided with a main venturi 85 which lits tight'vwithin the side walls ot the cylindrical-barrel portion 86. A second Venturi'membe'r of smaller diameter, has `its upper end, projecting slightly beyond the most restricted portion lot the main venturi 85and the tip "68, ofthe nozzle unit projects into Vthe secondary or smaller.l

venturi so that the openings in the top of the tip are placed slightly beyond the most restricted portion of the secondary ven turi 87. In the design of any carburetor there are two essential requirements, which to a certain extent oppose one another;- to deliver a maximum charge of air to the engine, and to exert the maximum atomizing effect upon the fuel, which maximum atomizing effect is more or less a function of the suction or force by which the fuel is drawn from the nozzle. A strong suction on the nozzle usually involves a high velocity past it, and to obtain a higher velocity in an ordinary single Venturi carburetor generally involves a considerable vacuum or depression in the intake manifold of the engine. This means that the air charge delivered to the engine is rarefied and of less density than would be the case if the air velocity were less, thus preventing maximum air charge if the suction on the nozzle is to be suflicient, while if the single venturi is made of such size as to operate properly at low air velocities it will not be adequate for the demand at high air velocity. By applicants arrangement only a small part of the air taken in by the motor is raised to high velocity, and the maximum charge of air is most efficiently secured on both low and high suctions simultaneously with a maximum suction upon the nozzle. This result is secured basically by the use of two Venturi tubes, with the secondary Venturi outlet disposed at the point of greatest depression in the large venturi, a most important point since improper relation of the tubes makes the desired action impossible; then improved by the air bleeding of the nozzle. This last-named point is important for this reason: it is an accepted fact that in an ordinary uncompensated carburetor the mixture tends to grow richer as the sut-tion increases. The double venturi partly counteracts this tendency by reason of the passage of aironly between the two venturis and the bleeding of air into the jet also vpartly counteracts this tendency, together rinmteracting it entirely or practi rally so. lf either of these devices were designed to do all the compensating their purposes would be defeated. If the bleed were made large enough to do so the liquid fuel would go out in slugs, and if the outer venturi were made too large it would not produce the desired effect upon the inner one. Thus, these two devices, by working togather and in harmony, have been found to produce the desired result. The secondary venturi is supported on the main venturi by means of a ring 88, having a series of spider arms 89, notched at their upper end to receive a. retaining ring 90 (see Figures 4, 5, and G) which retaining ring is preferably made of spring wire. The retaining ring 90 lies in a groove 91, formed in the outer surface of the main venturi 85, the spider arms 89 being set into slots cut into the bottom of the venturi so that the notched ends of the spider arms 89 lie Within the groove 91, so that the spring retaining ring 90 securely holds the spider arms in position. It will be noted that the spring retaining ring is provided with an inwardly extending portion 93, which is set into a hole in the main venturi. This prevents any tendency for the ring to slip around so that the opening might come in register with one of the spider arms. The spring retaining ring is further provided with offset spring portions 94, which. are adapted to cause the ring to ill the groove 91 laterally and hold the spider arms yieldingly in place to prevent vibration or rattling. The spring ren taining ring is thus held not only against circumferential displacement, that is by rotation in the groove 91, but also against lateral displacement in the groove 91, so that the spider arm is held against any possibility of dislocation or disconnection.

The lower end of the main venturi rests upon the shoulder or ledge 95, where the body member 2 joins the body member 1 so that there is no opportunity for the main venturi or the secondary venturi to drop down. The spring retaining ring is held in the groove by the side walls 86 of the body member within which the venturi is fitted.

The venturi is formed with a groove on its outer surface forming a 'chamber 97 when the venturi is in place within the bore of the tubular throttle housing 85, this annular space being in communication with the interior of the venturi through a series of openings 96, which connection subjects the annular chan'iber 97 to a predetermined suction existing at the points of the openings 96. This annular chamber 97 communicates with the top of the Boat chamber 3 by way of a passage 95 so that a predetermined suction or sub-atmosliheric pressure may be maintained wit-hin 4the 'float chamber, as will he described later.

ln a double unit of this character it is desirable to secure, as near as possible, an absolutely Iequal discharge of fuel from each of the ets or nozzle members 55-56. This is secured primarily by means of calibrated orifices in the calibrated plugs 60, shown in Figure 4. In order to secure a different rate of fuel feeding for adjusting the total quan` tity of fuel discharge by both nozzle units.. we have provided a novel form of control of the gasoline discharge by controlling the sub-atmospheric pressure within the float chamber' 3. The calibrated orifices GO divide the work equally between the nozzle units at all times and the .sub-atmospheric control of the float chamber controls the quantity of We provide a-controlling valve generally designated bythe reference .90. This control valve comprises a valve housing 100 formed integral with lthe upper body member 2 and placed substantially between the throttle housings 8o. y

The valve housing' 100 has a cov-er 101 adapted to be clamped on, the top of' the housing by means of the machine screws 102.

The interior ot tliefvalve housing.' provides a chamber 10.3 which coiiiiiiiiniciites with kthe atmosphere through the passageway 104. The passageway communicates lwith ati'nosphcre through a port 105l opening ,into the air intake as islshoivniii Figur-e 2. The

ample size to permit a t'ree passage .of air to the valve chamber 103. The valve casing provides a hat valve Vseat at the bottom,

.ulaiL'itedy to to-operate with ay rotary valvef.-l member i' t'or controlling theports 108 which open into theiioat chamber 1 The valve member 107 has a boss109 eX- tending down into a pocket in the valve seat'A 106 for centering the valve member. A circular boss or stem 110 is connected -by a.

transverse slot 111 and a tcnon 112 to a short o ieratino' shaft 113 Vwhich iro'ects through'Y a bearing 115` in the valve cover 101.

,The operating shaft 113 is provided withY a flange 110 adapted to bear on the under side ofthe valve cover 1014and this frange is pressed `against the same by means of a coil spring 11"?, which keeps the valve men'iber 107' upon its lseat and holds the langegllagainst the-bottom of the cover 101 to-prevent leakage of air past either of these niembers. The t-enon 1121s orn'ied integral with the operating shaft 113, :so that turning ot' the shaft operates the valve head 107. 'The shaft 113`is pinned to an operating arm 118, which operating arm is und-er tue control of the driver. The operating arni 118 is provided with a sector portion 119 (see Figure 1) inthe lower face ot" which sector porot theA -sorino )luneer 121. The sirino L o bn i l .c plunger 121I is guided in a suitable bore in .the hub 122 of the cover plate 121, the spring.

123 pressing the top ot' the plunger 121 the L ency for the tuel toy be drawn cutot` the nozzles andthus a difference in the eii'ectivc level inthe 'lioat chamber 'is secured.

. This sub-atmospheric condition is con trolled by theextent to which air is admitted to relieve the same. 'Vhen the valve disc .10T is moved so 'that the passages 108 are completely closed, the full sub-atniosplier;c etl'ect `Will be exerted in the float chamber.

Upon moving the valve disc to the position Where theopenings 124 register with the ports 108, .the sub-atn'iospheric condition Within the float chanil'ierz will be relieved to a greater or less extent, changing the eii'ec- 'tivelcvel in the iioat chamber accordingly.

AlVhen the o ieninojs are brought iii revis- .L t: A e.. 1 c

Ater with the.. ports 10S, the sub-atmospneric eiilect in4 the' float chan'iber is substantially eliniiiated. u I

rEhe pilot control valve 99 is useful in any type o1 carburetor and with any type of gasoline nozzle lbut We find that. there is a peculiar co-operation between the pilot control valve vand the air bled jet Which ive einploybecause ot' the greater controlling Ieffect which itis possible toexercise over the rate of 110W of the fuel.

The diagram of Figure 26 illustrates the action involved. This diagram shows the gasoline nozzle 56 having `the air bled port 77, The diagram of F igure 25 shows the nozzle 56 Without the air bled jet.

Assuming that in the smaller or secondaryventuri 87 a suction of one pound eX- isted and that the suction in the outer venturi at tlie'port 96 is .40 lbs., then the suction Within the float chamber 3 may be varied between .110 lbs. and 0 lbs. suction by adjustment vof the valve 99. f

New, assuming the same conditions to obtain in Figure 26, but that due to the air bleeding at the port 77 the suction exerted vupon th-e gasoline in the tube which supplies seen at #10 lbs.

the nozzle 5Gis .70 lbs., it will be once that the maximum suction ot' in the float chamber 3 will have a greater I .etlectiipon the 110W et gasoline subject only tion are provided a` number ofsockets 120` `adapted tojbe engaged by the rounded nose tol .70 lbs. as indicatet in Figure 26 than upon the -construction wherein the suction is 1 lb., tending to create a 'flow of the gaso- Ylin-e. The lan7 governing the rate of iiow due to pressure or to a static head is well known I as V2;`:2g7t. against the bottom of th-ej sector and tending 1n other Words, the rate ot' flow ot gasoline tothe nozzle 56 depends upon the square' root ot the pressure tending to pi'ouce said flow. In the airbled construction or' our invention We find that th-e air bleed- 'ping' does have a double function, iirst ot' breaking uptlie gasoline and permitting' it to tlowv"more freely and second to secure a .greater percentage otregulation or a greater 4range of variation ot oiv producible ny the operators control valve 99.

The idling jet designated as a whole by the reference character 126, has an opening under the lip of the throttle valve v13 as shown in Figure 9, for supplying mixture to the engine when the engine is idling. A. relatively large hole is cut through the sid-e wall of the throttle housing under the lip of the throttle valve 13 and a bushing 127, which forms an internal valve seat, is pressed into this hole. The cylindrical portion 128 which is pressed into the opening is milled so'that when th-e plug is forced into the hole the milled surfaceI will grip the bore of the hole and resist turning or loosening. The plug 127 is provided with a small axial bore 128 which forms the fuel discharge nozzle for the idling jet, lthis opening 128 being controlled by a tapered needle valve 129. A plug 130 is threaded into the outer end of the hole in the wall of the throttle housing to close the same, the lower end of this plug having a rim resting against the bushing 127 and securely holding the same in place. The needle valve 129 has a threaded stem 131 threaded in the outer end of the plug 130 and this stein is .secured at its outer end to a hollow valve operating button or handle 132 by which Athe needle valve 129 is adjusted. The valve handle 132 is in the form of a hollow cup fitting over the outer end of the plug 130 and heilig adapted to engage a spring plunger 133 seated in the side of the plug. The circular flange 134 of the plug 130, which flange engages the outside of the bushing 127, is perforated with a number of holes to permit the fuel which enters by way lof the vertical passage 135 to enter the interior of the plug and pass out at the valve port 128. A small packing nut 136 is threaded into the open end of the plug 130 and holds a suitable packing 137 about the stein of the needle valve 128.

The valve bushing 127 has a vertical bore 139 such as would be formed by drilling transversely through the milled portion of the bushing. A vertical slot 140 communi cates with the bore 139, the bore and the slot thus communicating with 'the valve port 128 to permit gasoline to flow from the valve to the interior lof the barrel. is the throttle valve 13 normally lies about midway across the slot 140, air will be free to enter below the valve, pass through the slot and the bore and out of the slot and bore above the valve. Difficulty has heretofore been experienced where the idling jet has consisted merely of a small circular opening, in that a slight movement of the throttle valve towards the open position has obstructed the idling jet or removed the current of air from it to such an extent that insufficient mixture or an improper mixture was formed. In the present oase a movement of the throttle 13 away from the closed position has no suoli disturbing effect as the opening is in the form of a vertical slot..

The variations in port area of the idling jet should follow substantially a straight line law for the small angles of change of the throttle valve which effect the idling jet. The slot does this eiilectively and a circular hole will not do so. For small changes of the throttle valve from closed toward open position, the conditions of suction above and of atmospheric pressure below the throttle do not materially change. As the throttle moves from the closed position the part of the slot exposed to suction increases and the part expoed to air or that which bleeds the suction decreases, thus a greater ell'ectirc feeding of gasoline is secured.

The vertical gasoline passageway 135 is connected by means of a vertical supply tube 141 and a transverse passageway 142, with the interior of the accelerating well (A.

TvVe have provided a novel priming jet for starting the engine as shown in detail in Figures 9 and 10. A small valve body is formed integral with the side walls of the barrel member. A valve plug MG is adapted to rotate in the cylindrical bore of the valve body, this plug having a passageway 1&7 therethrough adapted to conin'iunicate when the valve is in the open position with a passage MS registering with the vertical bore 139 in the valve bushing 127. At its upper end the valve passage 147 is adapted to register with the priming nozzle or passage lett). The valve plug 1116 is preferably formed with a slight taper in order to insure tightness of the same. A small valve operating handle 150 is connected to the plug and extends outward in suitable position to be readily accessible for starting the engine.

A holding spring 151, fastened in any suitable manner to the barrel n'ieinber, en-

a cam 152 on the opposite end of the valve plug 1116 and holds this plug in any position in which it is moved. l

For starting the engine. assuming that the lioat chamber is properly supplied with liquid fuel, the throttle valve is closed and the priming valves 146 are opened as shown in Figures 9 and 10. The engine is then turned over. Fuel is drawn from the float chamber by way of the accelerating well Gel through passages 142, 141 and 135, through the idling valve nozzle 123 and out by way of the priming` nozzle 149. -`When the engine starts under its own power 'the priming valves 146 may be moved to closed position, the engine then depending upon the idling nozzle to supply the necessary mixture for turning the engine over.

Air enters the open slot 140 beneath the lip of the throttle and passes up past the idling nozzle opening 128 and out by wav of the slot above the lip of the throttle. As the throttle valve is closed the suction exerted upon the idling nozzle ,is relatively high and causesfa 'suitable' flow of fuel at that point.

lllhen the throttle is moved from the closed positiona slight distance, the main nozzles will begin to function, fuel being drawn through the main nozzle 67 and out at the tip 68. The suction upon the main nozzles is increased by the multiplying effect of the double Venturi arrangement.

rEhe normal fuel level maintained by the float and valve is slightly below the level of the outlet of the main nozzles. i

The bleeding passages for the bleeding chamber and for the accelerating well are l'illcd with liquid fuel when the' device is at rest. As soon as suction is exertedupon the main nozzles the fuel in these bleeding passages will be discl'iarged through the main nozzle particularly' upon starting and for accelerating of the engine.

As soon as the bleeding 'openings in the bleeding chamber 7G are uncovered, air enters in radial jets, tending` to break up the stream of fuel in the main nozzle 67. Thus an air emulsion is secured which atomizes and .f'aporizes more easily. At the same time the desirable characteristics of an air bled jet are secured.

The air which enters the top of the accelerating well is 'partially drawn off through the radial openings 71 in the side walls of the main nozzle 67. rlhese openings further help to bleed 'the main fuel j'etand tend to maintain a condition of sub-atmosplieric pressure in the top of the accelerating well.

Upon further opening of the' throttle to4 accelerate the engine, the vincrease in suction exerted upon the main nozzle 67 draws some of the fuel out of the accelerating well by way of the opening 7b at the lower end of the main nozzle (S7, uncoifering the upper ones of the openings 7 2 in the side walls of the accelerating well casing. Thus a further reserve in the accelerating well is maintained for acceleration atlhigher speed.

The metering orifice in the plug @Ocontrols the rate of .How from the iloat chamber .to the main nozzle. Each nozzle is thus provided with a metering orifice to secure equal division of flow between the main nozzles. To reduce the effective flow through these orifices, the controlling valve may be operated to close olf the'atmosph'eric passageways S-1104i so that the 'suction exerted at tlie'openings 96 in the venturis operates upon the top of the float chamber. lf greater' veffective flow is to be 'secured the valve is moved so that this sub-atmospheric condition in the float chamber is relieved to the extent desired.

The openings '96 in the side walls of the venturi may bev employed to control the dethe rod 155.

grec of suction` exertedlupon the 'top of the float chamber. vliusby varying thefpositi'on, in the venturi, ofthese openings to draw lthe desired degree of Asuction from the venturi, the sub-atmospheric condition in the top of the float chamber may be correspondingly varied.

The nozzle yconstruction ofourinvention is designed to secure bleeding of the main jet without producing any irregularities of l'low such as are occasionedfby certain prior constructions. rlhe air which enters the main nozzle by way of the line openings 77 in the bleeding chamber 7 G, tend to form a fairly homogeneous mixture or emulsion. The particular Vfault of prior nozzle constructions is that the air lentering' the tube or nozzle tends to form bubbles which fill the bore of the tube so that 'alternate slugs of fuel and bubbles. oftairare proj cted out of the'nozzle. 'This tends to give an Airregular erratic action which is undesirable. The air which einers theV nozzle by way of the bleeding opening 71 in the top of the' accelerating well has a' si1nilareifect, due to the lineness of the openings and the fact that the air enters these openings in such a way as to be diffusedby the action'of the radial jets.

ln Figure 7 we have shown a modified form of main nozzle structure. ln this structure the sleeve 65 serves both as the inner wall of the accelerating ywell and as the main nozzle. This sleeve is provided with a series of openings 72 along the sides, the upper openings 7l corresponding to the openings 71 in the form shown in Figures 1 to 6, as they permit the air from the bleeding passageway 83 to pass into the column of liquid issuing from the main jet or nozzle. The radial openings 77 which open into the bleeding chamber 76 correspond to the opening 77 shown in Figures 1 to G.

A round rod 155 secured at its lower end to the screw plug 58, projects up through the bore of the main nozzle, being provided at its upper end with a head which is cut away at portions of its periphery to permit passage of the fuel. It is well known that the bubbles of air in the liquid fuel tend to assume a spherical' form and whenl these bubbles become sufhcientlydarge they tend to fill the bore of the tube forming the main nozzle, thus causing erratic feeding of the fuel. This appears to be due to the surface tension of the liquid. le have taken advantage ofthe surface 'tension in preventing the` formation of bubbles sufliciently large to fill the bore of the tube by inserting As the bubbles tend 'to retain a substantially spherical contour the rod 155 Atends to hinder the formation of'any bubbles which would fill the annular space between the `tube and the rod 155.

lnFigure 8 we have shown a ymodilied form of main. nozzle structure in which the sleeve lis similar in construction to that shown in Figure 7. However, instead of employing the rod 155 for breaking up the bubbles of air which enter the column of fuel, we provide a restricted orifice 156 for increasing the velocity of flow of the liquid as it enters the bore of the sleeve 6F. The purpose of this restriction 156 is essentially to increase the speed of flow and not to serve necessarily as a metering orifice, although this restriction niay be employed as ametering orifice.

By increasing the speed of flow at this point the tendency will be .for a stream of liquid to be projected into the bore ofthe sleeve 65 Without filling this sleeve complete-ly, so that the bubbles of air which enter by Way of the bleeding openings T2 will not have an opportunity for filling the bore of said sleeve. This action is particularly noticeable when the fuel has been drawn out of the accelerating Well so that an annular body of air surrounds the jet and prevents it from completely filling the bore of the tube.

We Wish to call particular attention to the position of the main nozzles with relation to the float chamber. The air entrance to the carburetor is faced toward the front of the airplane. l/Vithin the angles of approximately 40o climb or 800 dive, the float level Will be regulated Within the iioat chamber and Will be in normal relation to the main nozzles. On side slips or side dives a very large angle of inclination Will be permissible before the discharge hole on the float chamber to the uppermost jet is eX- posed to air, Which stops the discharge of gasoline from that jet. Ve have found that the ordinary type of float mechanism ceases to operate at angles of more than 30o from the vertical. Vhen `the float chamber is offset from the jet and the machine dives with closed throttle, the gasoline floods the entire motor. The float needle valve of our invention takes up vibration through the spring connection and keeps the needle point and needle seat from Wearing out.

The accelerating Well and main nozzle structure is adapted to secure a free bleeding action Without the objectionable irregularity in fuel feed.

The idling jet We have found to be a decided improvement over present construction. We find that the high suction on the idling jet extends to a much greater throttle opening than in any other construction with which We are familiar. This permits us to use a very large Venturi. tube, which is lhighly desirable, and at the same time yWe are able to get an intermediate range by the use of the throttle on the idling jet.

The operators control of the mixture is obtained by subjecting the float chamber to varying degrees of suction, taken from the main venturi. ln a 12cylinder motor carrying a four carburetor unit twins), it is practically impossible to adjust the four carburetor units to the same discharge. lVe therefore employ fired jets. lt is necessary, however, to have a control of the adjustnient and the means we employ, having fixed size metering orifices, allows of making the action equal on all four units. TWe can also use the controlling device shown on one carburetor float chamber and seal the other carburetor float chamber from atmosphere and determine the pressure in it above the gasoline by an equalizing connection from the :first mentioned fioat chamber, as shown in Figure 23. ln other Words, the second float chamber' is made a continuation of the first and therefore subject to the same subatmospheric conditions.

In Figure 23 We have shown the single control valve 99 as operating to control the pressure prevailing in the float chambers 3 and 3a of the two carburetor units Which supply mixture to the same engine. The float chamber is sealed up and communicates with the float chamber 3 by means of the equalizing tube 160.

The connection 95a of Figure 23 may be closed or may be left open. All that is essential is that the connecting tube 160 be large enough to equalize pressures.

The operators control valve 99 may be located at any convenient point as shown in Figure 24 with connecting tubes 161 leading to the various float chambers of the dierent carburetor units. In this case a small central chamber 169I is provided. From this central chamber upon which the valve 99 is mounted, the various pipes 161 lead to the float chambers of the different carburetors to maintain the degree of pressure on top of the liquid fuel in each float chamber at the same value to secure equal fiovv, which flow may be controlled in accordance With the Wishes of the operator.

The priming device of our invention is highly advantageous and forms, in connection with the idling jet suction, a very simple and effective device.

`We have provided an overflow connection 157 Which is tapped into a small draining Well 158 in the bottom of the carburetor intake. This overflow connection is led outside of the fuselage to discharge overboard any fuel which may be spilled.

l'n Figures 17v to 22 inclusive We have illustrated a modified form of carburetor embodying certain of the features of our invention. ln this construction the float chamber 3 has not been placed directly between the nozzles 55 and 56 but immediately behind and between said nozzles. rlhis construction is employed in order to bring the outlets 10 and 1.9.. as close together as possiA ble. The throttle valves '.lfl and 1? aremounted upon a, common shaft 14, which is adapted to be operated by the controlling lever 168. A pair of stop bracket arms 164- eontaining suitable set screws 165 ior adjusting the limits ot motion ot' the throttle valves 11 and 13 are Yfastened to a common hub, which in turn is attached to the throttle shait 14. At the opposite end of the shaft lei a throttle stem spring 166 shown in dotted lines in Figure 18 is mounted within the throttle stem cap 167, which in turn is pinned to the throttle sten: or shatt 14. rlfhis springbears against the interior o't the throttle stein cap and at the side bears against the throttle stem bushing 168 which, like the bushings 1G described in the previous embodiment, are preferably made ot brass or bronze. A washer 169 is interposed between the spring and the bushing 168. This arrangement ol the spring on the throttle sten'i'tends to hold the throttle in any given position and also tends to hold the parts tight so that they will not vibrate or rattle.

As shown in Figure 2O we have provided a removable gasoline strainer 17 O within the chamber 11 on the tank side of the float needle valve L16. fhis strainer is formed in the shape ot a 'truste-conical wire screen, the larger open end of which rests upon a cap member 171, which cap member has an opening fitting over the end of the valve seat member At its upper end the strainer 170 has a washer 172 between which and the top of the hollow eap 173 there is placed the compression spring 1741. This spring holds the strainer in place in such a manner as to prevent movement'or to prevent vibration and rattling.

In this modilieation the size ot the passageways between the float chamber 8 and the nozzle units and 56 is controlled by plugs GO having calibrated oritices.

The type of accelerating well and nozzle is substantially the saine as that shown in Figure 8.

Instead of drilling the bleeder passage way 78 from the rear in this modilication we drill 'the same from the front and close the open end by means ot the air bleeder channel plug 176. rThis plug consists el a machino screw. A locking clip 177 is held between two gaskets under the headot the plug 176 and this looking clip has a forked end like a wrench which engages the base of the tip 67 to prevent the same from unscrewin from the nozzle and well member 65.

rlhe accelerating well and the nozzle member is provided with an enlarged head which closes oill Athe bottom ol? the accelerating well 611, this well communicating with the float chamber 8 only through the restriction in the plug 156 through the channel 59 and the calibrated orifice in the plug v60.

Leanser 'lheidling well and nozzle structure herein differs from the prior embodiment. A tube 1&1 oit relatively small bore which has its lower end secured in the plug 175) which plug forms the idle tube holder, extends through the body of the throttle housing to vthe idling nozzle 126. rlhe idling tube 141 passes through the air passageway 7 9 which air passageway con'ununieates with the air in the air horn l by way ot the port 180. The idling tube 141 communicates through apertures `181 in the holder 17 9 and the'ehannel 1412 with the accelerating well ('34. lt will be noted that there is a passageway 178 along the side ol the accelerating well and nozzle member'65 which forms a communication between the bleeding passageway 78 and the top ot the accelerating well 64.

rl`he idling tube 111 bears at its upper end a nozzle having Va reduced bore controlling the tlow ot liquid fuel 'from the float chamber during idling. The plug member 127 has a vertical hole 139 which eon'in'umicates by way oit the vertical slot 14:0 with the interior of the throttle housing 12, this slot 14:0 lying immediately under the lip of the throttle valve 13 when the same is in closed position. rlhe plug 127 has a bore 128 through which the fuel mixture for idling passes on its way into the engine inaniitold.

The plug 127 has a lateral recess 188 lying immediately above the idling nozzle 182 and communicating with the bore 128. A channel vor annular space 1841 is termed about the inner end ot' the plug 127, this channel or annular space forming an air space for air which is admitted by way of the port 185, valve port 186' andv radial port 187 in the idle adjusting plug 130. The idle adjusting plug is threaded into the opening in which the nozzle member 127 is seated, this plug being screwed against the rear end of lsaid plug 127, to hold vthe saine lirmly in position.

A needle valve 129 is threaded into the hub or extension 188 of the adjusting yplug 180 for controlling the amount of air which enters by way of the ports 185 to form in connection with the liquid fuel entering from the idling nozzle 182, a mixture or supplying the engine during idling.

The construction of the idling needle valve is novel and l'orms an important improvement in this particular part ot the ap paratus.

The needle valve 129 con'iprises a suitable cylindrical stein which is threaded to rlit within the boss or extension 188 and has a slot or other suitable means for applying an adjusting tool such as the screwdriver. rlhis valve member has a diametrical hole near the outer end of the same, a spring and a pair of spherical rollers lying in said bore as is shown in Figures 19 and 20. The in- 

